The present invention relates to an absorbent pants which have a waist opening and two leg openings, said pants include a pants layer, which during use of the pants is intended to be turned toward the body of the user, and an outer barrier layer, which is liquid-tight and placed outside the pants layer facing away from the body of the user during use of the pants.
Absorbent products in the form of diapers have been known for a long time, both for single-use and re-use. A fundamental task for such products is to be able to collect and store body fluids excreted by the user, i.e. urine and faeces. In this connection it is important to see to it that the product is so constructed that urine and faeces first and foremost can be introduced into the product in a secure manner, i.e. that liquid and faeces do not already miss their target during the moment of excretion and end instead up to one side of the intended acquisition area. It is further at least equally important to make sure that fluids and faeces which find the right acquisition area later cannot leak out from their storage regions.
Alongside these main tasks for diapers, there are also other important demands put upon them, for example they should fit comfortably and pliably at the right place on the user, they should not cause any skin irritation to the user and they should not be made of substances which can harm our environment.
In many respects the different demands from the user work together in the endeavour to construct as good a diaper as possible. For example, the fit of the diaper and its fastening system influence the diaper's ability to quickly and securely receive urine and faeces without any leakage arising. Most of today's disposable diapers are therefore equipped with some sort of elastic leg cuffs, with the intention that these should tightly close around the leg of the user, and in this way prevent leakage. A known example of such a diaper is described in U.S. Pat. No. 3,860,003. The diaper has leg cuffs or side flaps outside the absorption body, which have pretensioned elastic bands applied to them. The intention is that the elastic bands shall contract the side flaps and in this manner form an elastically contractable contact line between the leg cuff of the diaper and the skin of the user. However, there is still a very large risk for leakage because there is only a relatively narrow contact line which is supposed to prevent the fluid which is not immediately absorbed by the absorption body from running out over the edges of the diaper. The pressure on this narrow line can be rather high and the fluid, does not have a very large distance to travel before it passes the contact line once the contact is no longer sufficient to withstand leakage. Furthermore, a large tensioning of the elastic band is required to ensure that the leg cuff does not lose contact with the skin of the user. This can in turn lead to a problem, namely chafing of the skin. Even if the leg cuffs would be able to resist the pressure from the fluid and not let it pass by, the fluid would instead accumulate above the absorption body and cause the skin to be moist, which in itself can lead to skin irritations.
With the aim of increasing the security against leakage, especially of loose faeces, past the side flaps or leg cuffs of the diaper, many of today's diapers are equipped with extra barrier flaps inside the elastic leg cuffs. An example of such a diaper is shown in EP 0 219 326. This patent has an object, among others, to achieve a diaper with double leakage protection and to create a channel with the help of the raised barrier flap, which would be able to retain body fluids in the diaper. The barrier flap is raised, among other places, along the inner part of the thigh of the user in the crotch region.
Body fluids which are not immediately absorbed by the absorption body in the diaper, for example loose faeces, are stopped by the barrier flap and are collected in the said channel. If body fluids nevertheless should manage to run past the barrier flaps, it is stated that the leg cuffs (the gasketing cuff) will form a further barrier against leakage. Even if the diaper according to EP 0 219 326 is equipped with a further barrier inside that already known, it still has the same disadvantage as the latter, i.e. that there is only a narrow line of contact against the skin of the user. This narrow line of contact can easily lose contact with the skin of the user when the barrier is subjected to a large pressure from, for example, a large quantity of urine. It has obviously been considered that the barrier flap will not be sufficiently resistent to prevent fluid from escaping over the barrier, as the precaution has been taken to have the elastic leg cuffs outside the barrier flaps. In the same way as for the known elastic leg cuffs, this still leaves a large area (even if it is a smaller area than earlier) of the skin of the user open to exposure to the fluid or faeces which collect in the so-called channel between the barrier flap and the absorption body, i.e. the risk for skin irritation is evident. This barrier construction is therefore far from being perfect.
It must be observed that there are also diapers on the market like the diaper described in the patent, which are equipped with a similar leakage barrier around the waist opening part of the diaper. The problem with leakage is therefore not only limited to the leg openings of the diaper.
Recently, a new type of diaper has been produced and launched on the market, the so-called pants diaper. These differ from the traditional diapers first of all with respect to the fastening system, i.e. the system which makes the pants diaper, respectively the normal or “open” diaper, stay in place on the user. Open diapers are sealed to form a pants on the user by means of fastening means of various types, for example adhesive tape ribbons, hook and loop fasteners or press studs. Pants diapers are, on the other hand, sealed at the edges already during manufacture so as to form a pants which has a waist opening and two leg openings. The sealing of the side seam in the respective side parts can be made in many ways, for example by means of a straight glue joint or a welded seam. The pants cover of the pants diaper can also be included as part of the fastening system of pants diaper. By this, it is meant that the cover because of its elastic capacity holds the pants diaper tightly around the body of the user and prevents the pants diaper from slipping down on the user. Naturally, there are other factors which influence the ability of the pants diapers to stay put at the intended place on the user. The difference between pants diapers and open diapers lies in that the latter can be tightened around the waist of the user by means of the fastening means, in the same way one can tighten a waist belt on a pair of long pants. Pants diapers are, however, not equipped with such tightenable fastening means, but must normally rely on their elastically tight covering.
There are many known pants diapers, for example those shown in EP 0 320 991. This pants diaper has a central absorption unit and two elastic side panels which are joined with the side edges of the absorption unit. Together they form a waist opening and two leg openings. The pants diaper is, in a way which is known for open diapers, furthermore equipped with elastic means along parts of the leg openings and the waist opening. The absorption unit comprises an absorption body between a liquid-permeable inner covering layer and a liquid-impermeable outer covering layer. The space between the inner covering layer and the skin of the user will be extremely limited, and consequently faeces which are deposited on the inner covering layer are liable to be in contact with the skin of the user and to be smeared over it. The inner covering layer will also become wet from the urine given off by the user. It is obviously not desirable that the skin of the user shall be in contact with a moist covering layer, which will be the case in the parts of the inner covering layer which at least occasionally come into contact with the skin of the user.
A characteristic for known pants diapers (and also for known open diapers) is that it is the outer covering layer, i.e. that which is applied outside the absorption body, which forms the load-bearing covering layer of the pants. This load-bearing covering layer is defined as the covering which one is left with, if one takes away all layers and elements comprised in the pants which do not actively contribute to form a waist opening and two leg openings of a pants, and without which the pants would no longer be able to be held together around the body of a user. Especially important load-bearing parts are the so-called side seams, i.e. the parts of the pants in which the front and rear parts of the pants-forming layer are joined in order to form the waist opening and the leg openings.
The load-bearing pants-forming covering layer for the known pants diaper according to EP 0 320 991 is formed of the two elastic side panels. The outer covering layer is applied outside the absorption body. In this case, the load-bearing pants-forming covering layer is made up of several pieces of material joined together. When the absorption body is filled with urine, the weight of the absorption body presses against the outer covering layer applied outside the absorption body, subjecting it to an increasing gravitational force, which in turn is transferred to the elastic side panels and the inner covering layer to which the outer covering layer is joined. This leads to the elastic side panels being stretched out and to the distance between the user and the inner covering layer increasing, thus, increasing the risk of leakage.
Another example of a pants diaper in which the outer covering layer forms the load-bearing pants-forming layer is WO 88/07337. In this case the outer covering layer is elastic. The absorption body is applied inside the elastic pants-forming covering layer as reckoned towards the body of the user.
In an attempt to improve the gripping and mounting characteristics of a pants diaper, it has been suggested in WO 93/17648 to equip a pants diaper with an elastically stretchable region in the front and/or rear parts of the pants diaper, while the crotch part is comparatively unstretchable. This pants diaper is however still traditionally constructed, in so far as the outer covering layer of the pants diaper forms the pants-forming layer of the pants diaper and that the absorption body in this way is arranged inside this pants-forming layer.
It has further been suggested to equip open diapers with a covering layer facing towards the user with one or more openings for the passage of urine and/or faeces down to a sort of pocket with an absorption body as the bottom of the pocket, in order in this way to isolate the skin of the user from contact with above all faeces. In U.S. Pat. No. 4,662,877 such a diaper is shown which comprises an upper layer, directed towards the body of the user and equipped with an elongated opening. Elastic bands are arranged along the edges of the opening with the intention of forcing the edges of the opening up from the absorption body lying below. Other elastic arrangements are also conceivable according to this patent.
EP 0 359 410 describes a similar diaper which has an elastic covering layer, equipped with an opening, which faces the body. An empty space is formed between the covering layer and the absorption core.
By analogy with the pants diaper above, it is noticeable that even if the covering layer of the diaper facing towards the user gives more liberty than that which has been the case for earlier known diapers with covering layers facing towards the body, it is still the outer covering layer of the diaper, i.e. the layer which is applied outside the absorption core as seen from the user, which is the layer that supports the diaper during use of same, i.e. after the diaper has been taped together with the fastening tapes on the user. The load-bearing outer covering layer is also at a distance from the body of the user, which leads to a large uncertainty concerning the position of the possible leakage barriers in relation to or contact with the genitals respectively anus of the user.
Finally, it is also known from U.S. Pat. No. 4,756,709 to arrange elastic zones with mutually different elastic directions of force in a pants-forming outer covering. In rear and front waist parts of the covering the covering is stretchable in the cross direction and in the intermediate crotch part it is stretchable in the longitudinal direction. This pants-forming covering layer, like those enumerated above, is arranged outside the absorption body.